SEATTLE — A suspected outbreak of norovirus is being investigated at the Pho Aroma restaurant in Seattle, Public Health — Seattle & King County said Thursday.

On Jan. 16, Public Health learned of three ill persons from one meal party became ill after consuming food and beverage from the restaurant, which is at 5605 Delridge Way SW, on Jan. 13, the department said.

Investigators closed the restaurant on Wednesday, and learned that two employees had experienced similar symptoms after the ill customers’ meal on Jan. 13.

“We do not have laboratory confirmation of the pathogen responsible for the illness, but symptoms are suggestive of norovirus. Often in norovirus outbreaks, no laboratory testing is done. The exact food or drink item that caused the illness has not been identified, though this is not uncommon for norovirus outbreaks where multiple food items may be contaminated,” the department said.

Meanwhile, the Tacoma-Pierce County Health Department said that as of Thursday, there had been a total of 542 cases of sickened people from norovirus — 520 from the El Toro Restaurant in Tacoma and 22 suspect cases from the El Toro Restaurant in University Place.

The department said it wouldn’t be issuing any more updates because of a large drop recently in cases being reported.